Patients undergo blood sample collection periodically for pharmacokinetic, immunogenicity, and other correlative studies. Samples are analyzed for serum levels of IGF-I, IGF-II, IGF-BP3, growth hormone, insulin, and C-peptide; trough concentrations and PK sampling; and biomarkers, including IGF-IR expression and phosphorylation and insulin receptor expression and phosphorylation via immunoprecipitation and Western immunoblotting. Tumor tissue samples from patients with Ewing sarcoma/peripheral PNET are banked for future research.